JPS58187537A - Controller of fuel injection quantity - Google Patents

Abstract

PURPOSE:To enable highly precise control of an injection quantity by an inexpensive device, by carrying out overflow control through a solenoid valve, in a device controlling an injection quantity by making a part of fuel to be boosted by a plunger in a distribution type fuel injection pump overflow. CONSTITUTION:Fuel sucked in through a suction port 16 by a plunger 2 which is moved in a rotary reciprocating state by a face cam 3 and is boosted in a pump chamber 5 is fed to an injection nozzle by pressure through a distribution port 6 to each cylinder. In an injection pump lik this, a solenoid valve 8 provided with a spool-form valve plug 8a is arranged on one end of an overflow port 7 which is in a connecting state always by applying pressure of the pump chamber 5. High pressure fuel inside the chamber 5 is made to overflow to a low pressure side and fuel injection is completed by the solenoid valve 8 when the valve 8 is opened by a control signal from a computer 9. Then, the computer 9 generates control signals based on outputs of a revolving sensor 10, a load sensor 11 and a bottom dead point sensor 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection amount control device in a fuel injection device for an internal combustion engine.

Injection I adjustment in conventional distribution type fuel injection pumps is performed by moving a ring-shaped member that opens and closes the overflow boat in the axial direction of the plunger (1) using a mechanical governor, as is well known, and changing the effective pumping stroke of the plunger. It is done by causing. However, when trying to electronically control the injection amount, if the above configuration is followed as is, it will be difficult to precisely control the position of this ring member.
This requires a high-grade actuator, position sensor, etc., making it complicated and expensive.

In view of the above, an object of the present invention is to provide an inexpensive and simple injection amount control device that controls the injection amount using a solenoid valve without using a ring-shaped member or a precision actuator.

The present invention will now be described with reference to embodiments shown in the drawings.

FIG. 1 shows a configuration including a partial cross section of an injection pump in which the present invention is applied to a known face cam type distribution injection pump 1 for diesel engines. This pump 1 pressurizes fuel sucked in from a suction boat 16 in a pump chamber 5 serving as a pressurizing chamber by a plunger 2 that rotates and reciprocates with a face cam 3, and then pumps the fuel sucked back from a distribution boat 6 for each cylinder. It is of the type that is pumped through 4 to a nostle not shown in the figure.

(2) In the present invention, in addition to the configuration described in L, a solenoid valve 8 having a spool-shaped valve body 8a is arranged at one end of the overflow port (overflow passage) 7, which is constantly connected to the pressure of the pump chamber 5. However, when this solenoid valve is opened, the commercial fuel in the pump chamber 5 overflows into the low pressure housing. The opening/closing operation of this solenoid valve 8 is controlled by a computer 9 as a control circuit.
controlled by.

On the other hand, the computer 9 includes a known rotation sensor 10, such as a combination of an electromagnetic big amplifier and tooth-like protrusions carved into the flywheel of an engine (not shown) at regular crank angles. A potentiometer-type load sensor 11 that generates a corresponding output in response to the driver's depression of the accelerator.
(If necessary, it is also possible to use an idle switch 12 that detects the idle state at the accelerator pedal), and the pump camshaft (plunger 2
A bottom dead center sensor 13 (not necessarily a bottom dead center (3)) consisting of a combination of an electromagnetic pickup and a projection provided at a position corresponding to the bottom dead center of each cylinder (coaxially integrated with the bottom dead center of each cylinder) A known temperature sensor 14, pressure sensor 15, etc. that detect cooling water temperature, intake temperature, atmospheric pressure, intake pressure, etc. are connected, and the computer 9 continuously detects the operating status and environmental status of the ENON. It is configured so that it can be done.

Next, the detailed configuration inside the computer 9 will be explained according to FIG. In FIG. 2, the part surrounded by a line U4 is a computer, and in this embodiment, a case of digital control using a microcomputer will be described. The configuration is centered around a central processing unit (CPLJ) 101, and a timer unit lo that generates time signals used for calculations and control.
2. An interrupt control 8103 that starts a predetermined interrupt process based on information given from the outside, a digital human-powered boat lO4 that manually inputs digital signals from the F dead center sensor 13 and the idle switch 12, and a digital human-powered boat lO4 that manually inputs digital signals from the rotation sensor 1o. A kind of frequency-voltage (F-Vl
Rotation number run (4) which is a converter Taunisoto 105, load sensor 111 pressure sensor 14,
It consists of an analog input port 109 for manually inputting analog information such as the temperature sensor 15, a memory 107 that stores various characteristic data necessary for control, and an output circuit section that controls the opening and closing of the solenoid valve 8 as an actuator. Each of these units 101-108 is connected by a path line 104 for mutually exchanging input/output signals.

Next, the operation of this embodiment will be explained using the flowchart shown in FIG. When the plunger 2 (integrated with the camshaft) of the injection pump l rotates and reaches the F dead center of a certain cylinder, a bottom dead center signal is sent from the bottom dead center sensor 13 to the computer 9. When this F dead center signal is input manually to the digital input board 104 in the computer 9 (step 201), the interrupt control unit 103 is activated and the interrupt processing shown in FIG. 3 is started in the CPU 01. (Step 202). At the same time as the interrupt starts, the CPU 01 starts counting time in step 203 using the timer 102, and in step 204
This commands the output circuit section (5) 108 to close the solenoid valve 8.

This interrupt processing flows through steps 202 to 213, and in steps 205, 206, and 207, the rotation speed, load, temperature,
The pressure information is taken in and stored in the memory 10 in step 208.
For example, a two-dimensional map is searched based on the electromagnetic valve closing time data T1 and the negative value stored in advance in 7 to obtain C. (
The longer 'r1, the longer the overflow caused by the electromagnetic valve 8 is delayed, the longer the injection pump (2) takes to pump the fuel, and the more the injection amount increases. That is, the memory 107 stores T I corresponding to the optimum injection amount according to the load and rotation speed). Then, in step 209, the valve closing time is 1' depending on the temperature (for example, engine cooling water temperature, intake temperature) and pressure (for example, atmospheric pressure, intake pressure, etc.).
1 is corrected, and in step 210, the corrected solenoid valve closing time data Tl' is sent to the output comparison register in the CPU. This output comparison register activates the output circuit when the elapsed time from the reference time matches the preset time, and in the case of the present invention, interrupt start (
In other words, start the counter from one point dead center of pump l,
6) When the time TI' set in step 211 is reached, the output circuit 108 is commanded to open the solenoid valve 8 in step 212.

During the above process, in the injection pump l, the plunger 2 moves into the pump chamber 5 as the cam 3 lifts due to the rotation of the plunger.
The pressure feeding of the fuel (inhaled in advance from the suction boat 16) is started, and the pressurized fuel is sent from the distribution boat 6 through the suction valve 4 to the nozzles disposed in each cylinder of the engine, and the fuel is Fuel is injected when the pressure reaches the nozzle opening pressure or higher. Then, when the time TI' calculated by the computer 9 has elapsed from the bottom dead center, the solenoid valve 8 opens as described above, and the ^-pressure fuel in the pump chamber 5 overflows into the low-pressure housing via the overflow boat 7. , the fuel pressure drops rapidly and fuel injection ends. That is, by arbitrarily changing the time Tl' until the solenoid valve 8 opens, the injection amount of the pump 1 can be arbitrarily controlled.

In the above-described embodiments, the injection pump main body is of the well-known face cam type, but the present invention is equally applicable to, for example, inch (7) cam type or outer cam type injection pumps.

In addition, in the above embodiment, the closing time of the solenoid valve was directly treated as 1 hour, but this can be handled in the computer as ``angle'' information such as crank angle or cam angle, and the same can be achieved by performing ``angle 1 hour conversion''. control will be put into practical use.

As described above, the present invention has a simple configuration in which a solenoid valve is provided in the overflow passage, and enables accurate electronic control of the fuel injection amount. It is sufficient to open the valve in order to ensure the passage diversion necessary for overflow, and since there are no problems with the device during opening or the behavior when closing the valve, a relatively simple structure can be used. Furthermore, since the fuel metering method of the present invention basically does not utilize the reciprocating motion of the plunger, for example, in an inner cam type pump, the fuel distribution member only rotates and does not reciprocate. Even in injection pumps to which the overflow method of injection 1 adjustment is not applied, the injection amount can be adjusted by overflow.

(8)

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing one embodiment of the present invention, FIG. 2 is a detailed configuration diagram of a control circuit in FIG. 1, and FIG. 3 is a flowchart showing an arithmetic processing procedure in the control circuit. l...Fuel injection pump, 2...Plunger, 5...
・Pump chamber forming a fuel pressurization chamber, 7... Overflow passage, 8.
... Solenoid valve, 4... Computer forming the control circuit, 1
0... Rotation sensor, 11... Load sensor, 13...
・-T" Dead center sensor, 14... Pressure sensor, 15...
・Temperature sensor. 101...Central processing unit. Representative Patent Attorney Takashi Okabe (9)

Claims (1)

[Claims] There is an overflow passage whose one end always communicates with the fuel pressurizing chamber of the fuel injection pump that pumps fuel to the internal combustion engine and whose other end communicates with the low pressure side, and an overflow passage that is placed in the middle of this overflow passage to open and close the overflow passage. the solenoid valve, an operating condition detector that detects various operating conditions of the engine, and a control circuit that calculates the opening/closing timing of the solenoid valve according to the detection signal of the operating condition and controls the opening/closing of the solenoid valve. . A fuel injection amount control device, characterized in that the fuel injection amount is determined by the valve closing period of the electromagnetic valve.